Concept of CDMA

• CDMA (Code Division Multiple Access)

• SSMA (Spread Spectrum Multiple Access)

RF Demod.

m(t)

Despread

RF Mod.

m(t)

Spread

M(f)

Baseband B.W.

RF B.W.

fc

System B.W.

(spreaded B.W.)

fc

spreaded

unspreaded

Spread Spectrum:

• Direct Sequence

• Frequency Hopping(Fast and Slow)

Fast: the change of fc greater than the

symbol rate.

Spread

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